Cardiac arrhythmias are a major clinical problem. We propose a significant and unique solution. Based on our preliminary results and progress with minimally invasive, multi dimensional image-guided interventions for myocardial ablation of cardiac arrhythmias in experimental animals, we have developed a theoretical basis and shown significant promise for proving the hypothesis that real-time, anatomy-based imaging and accurate fusion with electrophysiologic recordings will significantly improve the outcomes of catheter-based ablation of cardiac arrhythmias. In addition to greater success with less risk of morbidity/mortality, other important benefits will include reduced procedure time, less x-ray exposure, and lower cost. Our multi-disciplinary team (biomedical engineering, cardiology, radiology, computer science) will focus on atrial fibrillation (AF) where current treatment strategies are ineffective. However, our approach and system will be adaptable to treatment of any cardiac arrhythmias that can be reached by a catheter. The target goal is to achieve outcomes with catheter-based ablation comparable to surgical procedures, which can be 80-90% effective for AF, primarily due to direct visualization of the target cardiac anatomy through the surgically opened chest. But surgical procedures are undesirably invasive and accompanied by significant risk and cost. We will test our hypothesis by developing and validating a complete prototype system for image-guided catheter-based cardiac ablation featuring accurate real-time and on-line localization, visualization and targeting of the treatment region. This new system will be based on rapid volume image acquisition, real-time computer image processing and interactive display of three-dimensional anatomical images registered and mapped with electrophysiological data during successive cardiac cycles - a five-dimensional image guided intervention system. The system will be constructed using currently available microprocessors, display technology, mapping hardware and standard interfaces for 3D imaging modalities, including electron beam, CT, multirow spiral CT, MRI and ultrasound. Image processing steps, including segmentation, registration, modeling and rendering will be performed by customizing and optimizing algorithms previously developed and evaluated in our laboratory. The systems engineering task will essentially be one of designing, assembling and testing the integration of physical components (hardware, software and data) and procedural components (tasks) which have been separately developed and successfully demonstrated. This prototype system will then be thoroughly validated in the animal laboratory, with modifications and refinements for improved performance and user interface incorporated as these are indicated during the evaluation studies. We firmly believe that development, validation and optimization of this prototype system will herald a new generation of advanced technology for minimally invasive treatment of cardiac arrhythmias that will dramatically and positively impact the field.